package thread.cas;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicReference;
import java.util.concurrent.atomic.AtomicStampedReference;

/**
 * @author jiangwz
 * @create 2019/9/13.
 */
public class ABAQuestionSolve {

    static AtomicReference<Integer> atomicReference = new AtomicReference<>(100);
    static AtomicStampedReference<Integer> atomicStampedReference = new AtomicStampedReference<>(100, 1);

    public static void main(String[] args){

//        testABA();
        testABAQuestionsSolve();

    }

    // 完美解决ABA
    private static void testABAQuestionsSolve() {
        System.out.println("======== ABA的产生===========");
        new Thread(() -> {
            int stamp = atomicStampedReference.getStamp();
            System.out.println(Thread.currentThread().getName()+"第一次的版本号:" + stamp);
            try {
                TimeUnit.SECONDS.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            atomicStampedReference.compareAndSet(100, 101, atomicStampedReference.getStamp(), atomicStampedReference.getStamp()+1);
            System.out.println(Thread.currentThread().getName()+"第二次的版本号:" + atomicStampedReference.getStamp());
            atomicStampedReference.compareAndSet(101, 100, atomicStampedReference.getStamp(), atomicStampedReference.getStamp()+1);
            System.out.println(Thread.currentThread().getName()+"第三次的版本号:" + atomicStampedReference.getStamp());

        }, "t3").start();

        new Thread(() -> {
            int stamp = atomicStampedReference.getStamp();
            System.out.println(Thread.currentThread().getName()+"第一次的版本号:" + stamp);
            try {
                TimeUnit.SECONDS.sleep(3);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            boolean result = atomicStampedReference.compareAndSet(100, 200, stamp, stamp + 1);
            System.out.println(Thread.currentThread().getName() + "更改成功了吗? result=" + result + " 当前版本是多少? "+ atomicStampedReference.getStamp()
            + " 当前值是多少? " + atomicStampedReference.getReference());
        }, "t4").start();
    }

    private static void testABA() {
        System.out.println("======== ABA问题的解决===========");
        new Thread(() -> {
            atomicReference.compareAndSet(100, 101);
            atomicReference.compareAndSet(101, 100);
        }, "t1").start();

        new Thread(() -> {
            try {
                TimeUnit.SECONDS.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(atomicReference.compareAndSet(100, 200) + "\t" + atomicReference.get());
        }, "t2").start();

    }
}
